BIOLOGICAL APPROACH

Assumptions about causes:Same as physical illness

Brain anatomy

Infection Neurotransmitters/Chemical

imbalance Genetics

Chemical imbalance

Levels of chemicals in brain too high or too low

These chemicals transmit signals between nerves

Chemicals called neurotransmitters

Vesicles release neurotransmitter into synaptic cleft

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Neurotransmitter binds to receptors & activates them

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Enzymes are released to break down the neurotransmitter

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Excess neurotransmitter is taken up by the pre-synaptic neuron

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Vesicles are replenished with new & reused neurotransmitter

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Chemical imbalance

Levels of neurotransmitters may be too high or too low

Depression- too low serotonin Schizophrenia – too high dopamine

Infection

Bacteria and viruses may lead to mental disorders

streptococcus infection has been linked to OCD in some children

glandular fever linked to anorexia (only 4 patients) Today Show Saving Sammy PANDAS -

YouTube

Neuroanatomy Damage to brain structures May be abnormal from birth or due to injury E.g. hypothalamus role in eating disorders Ventricles and schizopheniaEvidence: In mice if hypothalamus cut they either

starve or overeat

Mouse lesion hypothalamus

Schizophrenic twins

Genes inherit a tendency for mental disorders in

DNA from parents Tested using: Family studies e.g. schizophrenia 18x more

likely if 1st degree relative with it Twin studies e.g. Comparing MZ (identical)

& DZ twins Concordance rates (both have disorder) Anorexia MZ 56%, DZ 7% Bipolar disorder MZ= 80%, DZ= 16% Gene

Found At The Root of Hair-Pulling Disorder - YouTube